Glazed doors and windows (i.e. doors and windows with a glass panel) can be framed with a variety of materials. These include wood, fiberglass, polyvinyl chloride (PVC), or metal. Wood frames and wood sashes are generally more energy efficient than their all-metal frame and sash counterparts because wood is a better thermal insulator than metals such as aluminum or steel. In certain applications, wood frames are often chosen over metal for their natural appearance, especially within a building interior. A disadvantage of wood-framed doors and windows is that their frame and sash exteriors are vulnerable to sun and rain. These exterior surfaces can be “cladded,” or covered with aluminum or other materials, to resist the elements and improve durability. The interior of the wood frame or sash can remain uncladded to retain its natural appearance.
In the United States, aluminum cladding is typically applied directly, and often permanently, to the surface of the wood frame or sash. American-style cladding is typically made of rolled or formed aluminum so it can easily be applied directly to the surface of the wood frame.
In Europe, there is a movement toward energy efficient aluminum-clad wood doors and windows with a pleasing architectural appearance. These are known in the art as Euro-style aluminum-clad wood door and windows or simply “Euro-clad.” They often go by designations such as Euro-style IV 68, Euro-style IV 78, Euro-style IV 92, or Euro-style IV 110. The “IV” designation indicates insulated glass. The numerical designation such as 68, 78, 92, or 110 indicates the thickness in millimeters of wood frame and/or the wood sash. Euro-clad windows such as Euro-style IV 78 and thicker enjoy good frame and sash rigidity as well as better thermal and noise insulation because of the thickness of wood frames and sashes. Euro-style cladding often includes thick complex ribbing to add structural integrity and to provide air breaks between the cladding members and wood frame. Euro-style cladding is typically made of relatively thick extruded aluminum, and enjoys greater structural rigidity than thin rolled and formed aluminum found in American-style cladding.